Stability Of Ag-Iii Towards Halides In Organosilver(Iii) Complexes

The involvement of silver in two-electron Ag-I/Ag-III processes is currently emerging. However, the range of stability of the required and uncommon Ag-III species is virtually unknown. Here, the stability of Ag-III towards the whole set of halide ligands in the organosilver(III) complex frame [(CF3)(3)AgX](-) (X=F, Cl, Br, I, At) is theoretically analyzed. The results obtained depend on a single factor: the nature of X. Even the softest and least electronegative halides (I and At) are found to form reasonably stable Ag-III-X bonds. Our estimates were confirmed by experiment. The whole series of nonradiative halide complexes [PPh4][(CF3)(3)AgX] (X=F, Cl, Br, I) has been experimentally prepared and all its constituents have been isolated in pure form. The pseudohalides [PPh4][(CF3)(3)AgCN] and [PPh4][(CF3)(3)Ag(N-3)] have also been isolated, the latter being the first silver(III) azido complex. Except for the iodo compound, all the crystal and molecular structures have been established by single-crystal X-ray diffraction methods. The decomposition paths of the [(CF3)(3)AgX](-) entities at the unimolecular level have been examined in the gas phase by multistage mass spectrometry (MSn). The experimental detection of the two series of mixed complexes [CF3AgX](-) and [FAgX](-) arising from the corresponding parent species [(CF3)(3)AgX](-) demonstrate that the Ag-X bond is particularly robust. Our experimental observations are rationalized with the aid of theoretical methods. Smooth variation with the electronegativity of X is also observed in the thermolyses of bulk samples. The thermal stability in the solid state gradually decreases from X=F (145 degrees C, dec.) to X=I (78 degrees C, dec.) The experimentally established compatibility of Ag-III with the heaviest halides is of particular relevance to silver-mediated or silver-catalyzed processes.